import java.util.Scanner;

public class Xiaoming{
	public static void main(String[] args) {
      Scanner du = new Scanner (System.in);
		System.out.println("请输入分数");





    int a = du.nextInt() ;

	if(a > 80){
	System.out.println("A");
	}
else if(a > 70 && a <= 80){
	    System.out.println("B");
	}
	 else if(a > 60 && a<=70){
	    System.out.println("c");
	}
	 else if(a <= 60){
    System.out.println("d");
	}
}
